Construction Cost Estimating


How to use excel sheet to design a Raft Foundation

Raft foundations alias Mat Foundations belong to a large concrete slab that provides strong support to a number of columns and walls. The slab is expanded under the entire building or relatively a large part of it which reduces the contact pressure in contrast to the conventionally utilized strip or trench footings.

Raft foundation refers to a dense concrete slab that is reinforced with steel to cover the whole contact area of the structure like a dense floor. Occasionally area covered by raft may be more than the contact area based on the bearing capacity of the soil below. The reinforcing bars operate normally to each other in both top and bottom layers of steel reinforcement.

Mat/Raft Foundation is suitable under the following conditions :-

• If the soil has low bearing strength,
• Walls of the structure are very adjacent so that individual footings would over hanged.

• It is suitable for large loads,
• Individual footings would cover in excess of about half of the construction area.

Benefits of Raft Foundation

• Raft or mat foundation is cost-effective because foundation and floor slab are combined in it.
• Little excavation is necessary for raft foundation.
• It can make adjustment with mixed or poor ground condition.
• It decreases differential settlement.

Given below, the sample of an excel sheet to create the design of raft foundation.

To download the sheet, click on the following sheet

How to use excel sheet to design a Raft Foundation